Note 11. Fair Value Measurements (Details) - Balance Sheet Grouping (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	$ 168,993	$ 102,578
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	168,993	102,578
Foreign exchange forward contract assets	3,450	7,230
Restricted investments (excluding restricted cash)	286,145	301,216
Note receivable, affiliate	0	17,725
Notes receivable - noncurrent	8,969	9,260
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, including current maturities	562,217	562,572
Foreign exchange forward contract liabilities	3,834	5,036
Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	168,993	102,578
Foreign exchange forward contract assets	3,450	7,230
Restricted investments (excluding restricted cash)	286,145	301,216
Note receivable, affiliate	0	17,723
Notes receivable - noncurrent	9,020	9,371
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, including current maturities	563,989	565,879
Foreign exchange forward contract liabilities	3,834	5,036
Interest Rate Swap [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Swap contract liabilities	1,158	1,467
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Swap contract liabilities	1,158	1,467
Cross Currency Interest Rate Contract [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Swap contract liabilities	3,417	1,898
Cross Currency Interest Rate Contract [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Swap contract liabilities	$ 3,417	$ 1,898